crop losses
In order to minimize grain losses during mechanized harvesting, the first and most important care should be taken with regard to operating speed, since excess speed is the cause of large waste. The speed should vary from 1.5 to 6 km/h, but the ideal one must be found in the field, as it depends on the conditions of the area and the productivity of the crop. Each area, field or cultivar must be treated individually.
Axial harvesters support higher working speeds due to the greater processing capacity of the harvested material. The farmer should not make the decision to increase the operating speed as the function of the harvester's operational capacity (hectares/hour), but rather as the function of grain losses, so they are below tolerable levels.
Cutting and feeding unit
Cutting and feeding are done by the platform and the conductive channel, popularly called “neck”. Researchers indicate that around 70% of grain losses originate from cutting and feeding mechanisms (platform). Of these 70% losses on the platform, around 90% comes from the action of the reel, as it is the only component that “touches” the plant outside the machine. This is the first component to be checked, and the height, the distance from the snail and the inclination of the fingers should be adjusted, depending on the size or lodging of the plants.
Reel Height Recommendations
Regarding the height of the reel, it is recommended that it touch the crop as high as possible (for the soybean crop it should touch the upper third of the plant, for wheat just below the ear and for rice just below the panicle). Touching at an excessive height can cause losses due to tipping of the cut crop and low height of the reel, losses due to threshing and winding of the cut crop. The reel rotation speed should be determined based on the behavior of the plants that come in contact with the cutterbar, causing the product to immediately fall into the platform. Roughly, when observing the profile harvester, the farmer must have the impression that the reel is slightly pulling the machine, that it must be between 18 and 50% higher than the machine's working speed.
Cutter bars
Platforms can be rigid or flexible cutterbar. The flexible ones are used for crops carried out close to the ground, such as soybeans. Machines that have automatic positioning control systems facilitate the operation and increase the quality of work and, in general, require prior calibration to test all components, especially the sensors. The height of the cutter bar must be adjusted so that it works as close to the ground as possible (in the case of soybeans), or at a height sufficient to pick up the lowest grains, without taking excess straw into the machine (wheat, corn and rice). Some platforms allow the adjustment of the angle of the cutter bar, this is indicated for crops with creeping habit such as beans, for example.
Height of the "snail"
The auger, known as a “snail” should be adjusted so that the product is uniformly carried to the longitudinal conductor (neck). The height of this component must be as small as possible and varies with the type and volume of material collected. Excessive height in relation to the bottom of the platform results in the uneven feeding of the machine, as the separation that is too small will cause a previous threshing. Some machines have replaced the snail with a conveyor belt, which moves the material from the ends to the center of the platform, called a draper.
Conveyor Belt Adjustments
The main regulation component of the feeder channel, which transports the material from the platform to the track, is the conveyor belt, which must be adjusted in its positioning and tension (by means of the side tie rods), seeking uniform flow, without threshing or overloads for the cylinder. The rock collector (located at the end of the channel and before the trail) should be periodically cleaned and serviced.
Trail unit
The first adjustment concerns the opening between the cylinder and the concave. For soybeans and rice, it should be as large as possible, avoiding damage to the grains, but allowing the trail of all the material. For corn, this regulation is made according to the average diameter of the ears, so that the grain is threshed without being broken (good quality). Another important factor is the opening ratio, which must be 2:1, that is, the input dimension must be double the output. The adjustment must be made on the machine's lateral ties, with measurements according to the brand and type of harvester.
Rotation is determined in the operator's manual for each grain type and moisture condition. As variations in moisture content can occur during the course of a working day, as adjustments must be made according to the conditions observed. Cylinder rotation is usually regulated via belt transmissions and variable policies or by hydraulic motor (axial track). Excessive wear on the teeth or cylinder bars can make the threshing process difficult and lead to a reduction in the quality of the final product.
Separation and Cleaning Unit
For conventional machines, the adjustments and care of the separation unit are: adjustment of the extension of the concave, adjustment of the extension position of the first deflector curtain, the material of the curtain, which can be rubber or canvas, the number of blinds placed on the machine and the rotation speed of the rear beater. In axial flow harvesters, there is a great disparity in the components used by the manufacturers. However, as a general rule, you should check: the wear of the scraper bars, gums, concave, beaters and shaft bearings.
The cleaning system consists of a tray, sieves, upper and lower, extension of the upper sieve (screen sieve), fan and air deflecting plates. Basically, there are two adjustments to be made: opening the sieves, which should be as little as possible, and fan rotation, which should be as high as possible.
Criteria to define the opening of the sieves for soybean cultivation.
Screen Opening Criteria for determining opening
Top grain passage 15 mm plus 50%
Lower grain passage 10 mm
Pod passage 18 mm retract
General criteria to define the opening of sieves for the cultivation of wheat.
Opening sieve
Superior 10 to 13 mm
Lower 06 to 08 mm
Tip: the top sieve must be adjusted so that all unthrashed grains and cobs pass through. As a way of field regulation practice, it is centered that the operator fully close this sieve. Take a handful or two of grain and throw it over it. Then open this sieve until all the unthrashed grains and ears cross through it. In the lower sieve, only the clean beans must pass. Its opening will vary directly with the diameter of the grains of each crop. The grains and material that do not pass through this sieve will be directed to the trimmer.
Grain transport and storage unit
Elevators adjust the tension adjustments of the chains, usually made by the execution windows, located at the bases of the specific elevators. The correct tension must provide a slack, which allows a small lateral movement of the chain links and no vertical movement of the same. For moist grains with impurities, a wider opening should be left, with the grain dry and clean, the more closed position of the gutter is recommended.
Conclusion
In short, for grain losses to be as small as possible, it is necessary to: quantify them and know in which part of the machine they occur, in order to regulate; define the ideal working speed, which will depend on the type of trail system; and be up to date with maintenance, performed according to the maintenance plan specified by the manufacturer.
